The Mail Box Store of New Castle is always looking for ways to help our customers save money. The Mail Box Store of New Castle coupons are a great way to make your visit more valuable and we’re constantly changing and updating our coupons, so check back regularly to find other fantastic savings on Document Shredding, Notary Public, U-Haul Rental, Mailbox Rental, Antique Shipping, Package Drop-Offs and more!.